Thermal energy exchange model and water loss of a barrel cactus, Ferocactus acanthodes
The influences of various diurnal stomatal opening patterns, spines, and ribs on the stem surface temperature and water economy of a CAM succulent, the barrel cactus Ferocactus acanthodes, were examined using an energy budget model. To incorporate energy exchanges by shortwave and longwave irradiation, latent heat, conduction, and convection as well as the heat storage in the massive stem, the plant was subdivided into over 100 internal and external regions in the model. This enabled the average surface temperature to be predicted within 1 C of the measured temperature for both winter and summer days. Reducing the stem water vapor conductance from the values observed in the field to zero caused the average daily stem surface temperature to increase only 0.7 C for a winter day and 0.3 C for a summer day. Thus, latent heat loss does not substantially reduce stem temperature. Although the surface temperatures averaged 18 C warmer for the summer day than for the winter day for a plant 41 cm tall, the temperature dependence of stomatal opening caused the simulated nighttime water loss rates to be about the same for the 2 days. Spines moderated the amplitude of the diurnal temperature changes of the stem surface, since the daily variation was 17 C for the winter day and 25 C for the summer day with spines compared with 23 C and 41 C, respectively, in their simulated absence. Ribs reduced the daytime temperature rise by providing 54% more area for convective heat loss than for a smooth circumscribing surface. In a simulation where both spines and ribs were eliminated, the daytime average surface temperature rose by 5 C.
- Research Organization:
- Univ. of California, Los Angeles, CA (United States)
- OSTI ID:
- 6818330
- Journal Information:
- Plant Physiol.; (United States), Vol. 60:4
- Country of Publication:
- United States
- Language:
- English
Similar Records
Concomitant changes in high temperature tolerance and heat-shock proteins in desert succulents. [Agave deserti, Carnegiea gigantea, Ferocactus acanthodes]
Temperature, water availability, and nutrient levels at various soil depths-consequences for shallow-rooted desert succulents, including nurse plant effects. [Agave deserti; Ferocactus acanthodes; hilaria rigida]
Related Subjects
CACTI
ENERGY MODELS
ENERGY TRANSFER
HEAT LOSSES
HEAT STORAGE
IRRADIATION
PLANT STEMS
PLANTS
SEASONAL VARIATIONS
STOMATA
TEMPERATURE DEPENDENCE
WATER VAPOR
BIOMASS
ENERGY LOSSES
ENERGY SOURCES
ENERGY STORAGE
FLUIDS
GASES
OPENINGS
RENEWABLE ENERGY SOURCES
STORAGE
VAPORS
VARIATIONS
550000* - Biomedical Sciences
Basic Studies